freebsd-dev/include/llvm/Analysis/IVUsers.h
2009-06-23 14:50:01 +00:00

223 lines
7.6 KiB
C++

//===- llvm/Analysis/IVUsers.h - Induction Variable Users -------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements bookkeeping for "interesting" users of expressions
// computed from induction variables.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_IVUSERS_H
#define LLVM_ANALYSIS_IVUSERS_H
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include <llvm/ADT/SmallVector.h>
#include <map>
namespace llvm {
class DominatorTree;
class Instruction;
class Value;
class IVUsersOfOneStride;
/// IVStrideUse - Keep track of one use of a strided induction variable, where
/// the stride is stored externally. The Offset member keeps track of the
/// offset from the IV, User is the actual user of the operand, and
/// 'OperandValToReplace' is the operand of the User that is the use.
class IVStrideUse : public CallbackVH, public ilist_node<IVStrideUse> {
public:
IVStrideUse(IVUsersOfOneStride *parent,
const SCEV* offset,
Instruction* U, Value *O)
: CallbackVH(U), Parent(parent), Offset(offset),
OperandValToReplace(O),
IsUseOfPostIncrementedValue(false) {
}
/// getUser - Return the user instruction for this use.
Instruction *getUser() const {
return cast<Instruction>(getValPtr());
}
/// setUser - Assign a new user instruction for this use.
void setUser(Instruction *NewUser) {
setValPtr(NewUser);
}
/// getParent - Return a pointer to the IVUsersOfOneStride that owns
/// this IVStrideUse.
IVUsersOfOneStride *getParent() const { return Parent; }
/// getOffset - Return the offset to add to a theoeretical induction
/// variable that starts at zero and counts up by the stride to compute
/// the value for the use. This always has the same type as the stride.
const SCEV* getOffset() const { return Offset; }
/// setOffset - Assign a new offset to this use.
void setOffset(const SCEV* Val) {
Offset = Val;
}
/// getOperandValToReplace - Return the Value of the operand in the user
/// instruction that this IVStrideUse is representing.
Value *getOperandValToReplace() const {
return OperandValToReplace;
}
/// setOperandValToReplace - Assign a new Value as the operand value
/// to replace.
void setOperandValToReplace(Value *Op) {
OperandValToReplace = Op;
}
/// isUseOfPostIncrementedValue - True if this should use the
/// post-incremented version of this IV, not the preincremented version.
/// This can only be set in special cases, such as the terminating setcc
/// instruction for a loop or uses dominated by the loop.
bool isUseOfPostIncrementedValue() const {
return IsUseOfPostIncrementedValue;
}
/// setIsUseOfPostIncrmentedValue - set the flag that indicates whether
/// this is a post-increment use.
void setIsUseOfPostIncrementedValue(bool Val) {
IsUseOfPostIncrementedValue = Val;
}
private:
/// Parent - a pointer to the IVUsersOfOneStride that owns this IVStrideUse.
IVUsersOfOneStride *Parent;
/// Offset - The offset to add to the base induction expression.
const SCEV* Offset;
/// OperandValToReplace - The Value of the operand in the user instruction
/// that this IVStrideUse is representing.
WeakVH OperandValToReplace;
/// IsUseOfPostIncrementedValue - True if this should use the
/// post-incremented version of this IV, not the preincremented version.
bool IsUseOfPostIncrementedValue;
/// Deleted - Implementation of CallbackVH virtual function to
/// recieve notification when the User is deleted.
virtual void deleted();
};
template<> struct ilist_traits<IVStrideUse>
: public ilist_default_traits<IVStrideUse> {
// createSentinel is used to get hold of a node that marks the end of
// the list...
// The sentinel is relative to this instance, so we use a non-static
// method.
IVStrideUse *createSentinel() const {
// since i(p)lists always publicly derive from the corresponding
// traits, placing a data member in this class will augment i(p)list.
// But since the NodeTy is expected to publicly derive from
// ilist_node<NodeTy>, there is a legal viable downcast from it
// to NodeTy. We use this trick to superpose i(p)list with a "ghostly"
// NodeTy, which becomes the sentinel. Dereferencing the sentinel is
// forbidden (save the ilist_node<NodeTy>) so no one will ever notice
// the superposition.
return static_cast<IVStrideUse*>(&Sentinel);
}
static void destroySentinel(IVStrideUse*) {}
IVStrideUse *provideInitialHead() const { return createSentinel(); }
IVStrideUse *ensureHead(IVStrideUse*) const { return createSentinel(); }
static void noteHead(IVStrideUse*, IVStrideUse*) {}
private:
mutable ilist_node<IVStrideUse> Sentinel;
};
/// IVUsersOfOneStride - This structure keeps track of all instructions that
/// have an operand that is based on the trip count multiplied by some stride.
struct IVUsersOfOneStride : public ilist_node<IVUsersOfOneStride> {
private:
IVUsersOfOneStride(const IVUsersOfOneStride &I); // do not implement
void operator=(const IVUsersOfOneStride &I); // do not implement
public:
IVUsersOfOneStride() : Stride(0) {}
explicit IVUsersOfOneStride(const SCEV *stride) : Stride(stride) {}
/// Stride - The stride for all the contained IVStrideUses. This is
/// a constant for affine strides.
const SCEV *Stride;
/// Users - Keep track of all of the users of this stride as well as the
/// initial value and the operand that uses the IV.
ilist<IVStrideUse> Users;
void addUser(const SCEV* Offset, Instruction *User, Value *Operand) {
Users.push_back(new IVStrideUse(this, Offset, User, Operand));
}
};
class IVUsers : public LoopPass {
friend class IVStrideUserVH;
Loop *L;
LoopInfo *LI;
DominatorTree *DT;
ScalarEvolution *SE;
SmallPtrSet<Instruction*,16> Processed;
public:
/// IVUses - A list of all tracked IV uses of induction variable expressions
/// we are interested in.
ilist<IVUsersOfOneStride> IVUses;
/// IVUsesByStride - A mapping from the strides in StrideOrder to the
/// uses in IVUses.
std::map<const SCEV*, IVUsersOfOneStride*> IVUsesByStride;
/// StrideOrder - An ordering of the keys in IVUsesByStride that is stable:
/// We use this to iterate over the IVUsesByStride collection without being
/// dependent on random ordering of pointers in the process.
SmallVector<const SCEV*, 16> StrideOrder;
private:
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
virtual void releaseMemory();
public:
static char ID; // Pass ID, replacement for typeid
IVUsers();
/// AddUsersIfInteresting - Inspect the specified Instruction. If it is a
/// reducible SCEV, recursively add its users to the IVUsesByStride set and
/// return true. Otherwise, return false.
bool AddUsersIfInteresting(Instruction *I);
/// getReplacementExpr - Return a SCEV expression which computes the
/// value of the OperandValToReplace of the given IVStrideUse.
const SCEV* getReplacementExpr(const IVStrideUse &U) const;
void print(raw_ostream &OS, const Module* = 0) const;
virtual void print(std::ostream &OS, const Module* = 0) const;
void print(std::ostream *OS, const Module* M = 0) const {
if (OS) print(*OS, M);
}
/// dump - This method is used for debugging.
void dump() const;
};
Pass *createIVUsersPass();
}
#endif